Lines Matching +full:disable +full:- +full:port +full:- +full:power +full:- +full:control
2 Advanced Configuration and Power Interface
5 force -- enable ACPI if default was off
6 on -- enable ACPI but allow fallback to DT [arm64,riscv64]
7 off -- disable ACPI if default was on
8 noirq -- do not use ACPI for IRQ routing
9 strict -- Be less tolerant of platforms that are not
11 rsdt -- prefer RSDT over (default) XSDT
12 copy_dsdt -- copy DSDT to memory
16 See also Documentation/power/runtime_pm.rst, pci=noacpi
26 If set to vendor, prefer vendor-specific driver
31 If set to none, disable the ACPI backlight interface.
40 Disable AML predefined validation mechanism
58 Documentation/firmware-guide/acpi/debug.rst for more information about
116 Format: <byte> or <bitmap-list>
119 Disable auto-serialization of AML methods
120 AML control methods that contain the opcodes to create
122 auto-serialization feature.
126 acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
130 Disable installation of static SSDTs at early boot time
140 Ignore the ACPI-based watchdog interface (WDAT) and let
141 a native driver control the watchdog device instead.
161 acpi_osi=! # disable all built-in OS vendor
163 acpi_osi=!! # enable all built-in OS vendor
165 acpi_osi= # disable all strings
200 is useful when one want to control the state of the
220 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
225 For broken nForce2 BIOS resulting in XT-PIC timer.
231 See Documentation/power/video.rst for information on
234 as soon as the kernel's real-mode entry point is called.
246 control method, with respect to putting devices into
247 low power states, to be enforced (the ACPI 2.0 ordering
267 off: disable AGP support
272 See Documentation/sound/alsa-configuration.rst
279 align_va_addr= [X86-64]
284 CPU-intensive style benchmark, and it can vary highly in
287 32: only for 32-bit processes
288 64: only for 64-bit processes
289 on: enable for both 32- and 64-bit processes
290 off: disable for both 32- and 64-bit processes
300 Allow execve() of 32-bit applications and setting of the
302 subset of the CPUs support 32-bit EL0. When this
303 parameter is present, the set of CPUs supporting 32-bit
305 and hot-unplug operations may be restricted.
307 See Documentation/arch/arm64/asymmetric-32bit.rst for more
310 amd_iommu= [HW,X86-64]
313 fullflush - Deprecated, equivalent to iommu.strict=1
314 off - do not initialize any AMD IOMMU found in
316 force_isolation - Force device isolation for all
321 force_enable - Force enable the IOMMU on platforms known
324 pgtbl_v1 - Use v1 page table for DMA-API (Default).
325 pgtbl_v2 - Use v2 page table for DMA-API.
326 irtcachedis - Disable Interrupt Remapping Table (IRT) caching.
328 amd_iommu_dump= [HW,X86-64]
334 amd_iommu_intr= [HW,X86-64]
337 legacy - Use legacy interrupt remapping mode.
338 vapic - Use virtual APIC mode, which allows IOMMU
340 This mode requires kvm-amd.avic=1.
344 disable
357 to the CPPC firmware. then CPPC power algorithm will
377 Power management functions (SPARCstation-4/5 + deriv.)
379 Disable APC CPU standby support. SPARCstation-Fox does
380 not play well with APC CPU idle - disable it if you have
387 when initialising the APIC and IO-APIC components.
388 For X86-32, this can also be used to specify an APIC
405 apm= [APM] Advanced Power Management
408 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
411 0 -- disable.
412 1 -- enable.
415 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
418 arm64.nobti [ARM64] Unconditionally disable Branch Target
421 arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory
424 arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension
427 arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication
430 arm64.nosme [ARM64] Unconditionally disable Scalable Matrix
433 arm64.nosve [ARM64] Unconditionally disable Scalable Vector
457 audit= [KNL] Enable the audit sub-system
459 0 | off - kernel audit is disabled and can not be
461 unset - kernel audit is initialized but disabled and
463 1 | on - kernel audit is initialized and partially
474 behavior is to disable the BAU (i.e. bau=0).
476 0 - Disable the BAU.
477 1 - Enable the BAU.
478 unset - Disable the BAU.
483 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
488 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
493 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
498 Disable BERT OS support on buggy BIOSes.
501 Disable BGRT to avoid flickering OEM logo.
505 See Documentation/block/cmdline-partition.rst
518 See Documentation/admin-guide/bootconfig.rst
523 bttv.pll= See Documentation/admin-guide/media/bttv.rst
532 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
551 inclusive. See arch/mips/include/asm/pgtable-bits.h
558 cgroup_disable= [KNL] Disable a particular controller or optional feature
559 Format: {name of the controller(s) or feature(s) to disable}
561 - foo isn't auto-mounted if you mount all cgroups in
563 - foo isn't visible as an individually mountable
565 - if foo is an optional feature then the feature is
569 cut the overhead, others just disable the usage. So
571 Specifying "pressure" disables per-cgroup pressure
574 cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
585 nosocket -- Disable socket memory accounting.
586 nokmem -- Disable kernel memory accounting.
587 nobpf -- Disable BPF memory accounting.
592 0 -- check protection applied by kernel (includes
594 1 -- check protection requested by application.
604 Disable CPUID feature X for the kernel. See
606 numbers X. Note the Linux-specific bits are not necessarily
607 stable over kernel options, but the vendor-specific
618 Also note the kernel might malfunction if you disable
627 force such clocks to be always-on nor does it reserve
631 information, see Documentation/driver-api/clk.rst.
633 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
650 [X86-32] pit,hpet,tsc;
657 [X86-64] hpet,tsc
662 Enable/disable the eventstream feature of the ARM
663 architected timer so that code using WFE-based polling
677 clocksource-wdtest.holdoff= [KNL]
683 cma=nn[MG]@[start[MG][-end[MG]]]
694 Sets the size of kernel per-numa memory area for
696 per-numa CMA altogether. And If this option is not
698 With per-numa CMA enabled, DMA users on node nid will
725 com20020= [HW,NET] ARCnet - COM20020 chipset
729 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
733 ARCnet - COM90xx chipset (memory-mapped buffers)
756 Use the specified serial port. The options are of
759 bits, and "f" is flow control ("r" for RTS or
762 See Documentation/admin-guide/serial-console.rst for more
772 Start an early, polled-mode console on the 8250/16550
773 UART at the specified I/O port or MMIO address,
775 MMIO inter-register address stride is either 8-bit
776 (mmio), 16-bit (mmio16), or 32-bit (mmio32).
780 the h/w is not re-initialized.
786 Use to disable console output, i.e., to have kernel
791 If the device connected to the port is not a TTY but a braille
807 syscall, or to executing "dmesg -S --raw" or to reading
822 Enable/disable the CPU sampling based debugging.
823 0: default value, disable debugging
826 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
828 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
831 disable the cpuidle sub-system
837 disable the cpufreq sub-system
845 [X86] Delay for N microsec between assert and de-assert
851 [SMP] Enable/disable parallel bringup of secondary CPUs
857 Run kdump after running panic-notifiers and dumping
870 [KNL, X86-64, ARM64, RISCV] Select a region under 4G first, and
873 See Documentation/admin-guide/kdump/kdump.rst for further details.
878 start-[end] where start and end are both
880 Documentation/admin-guide/kdump/kdump.rst for an example.
883 [KNL, X86-64, ARM64, RISCV] range could be above 4G.
890 [KNL, X86-64, ARM64, RISCV] range under 4G. When crashkernel=X,high
895 low memory is needed to make sure DMA buffers for 32-bit
899 --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
900 --> arm64: 128MiB
901 --> riscv: 128MiB
904 0: to disable low allocation.
909 [KNL] Disable crypto self-tests
917 csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
929 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
930 (one device per port)
931 Format: <port#>,<type>
932 See also Documentation/input/devices/joystick-parport.rst
945 [KNL] verbose locking self-tests
948 self-tests.
950 (no extra messages), setting it to -1 (all bits set)
951 will print _a_lot_ more information - normally only
958 parameter allows control of the order of pages that will
986 Format: { on, no-mount, off }
988 no-mount:
993 get a -EPERM as result when trying to register files
997 Default value is set in build-time with a kernel configuration.
1009 Documentation/admin-guide/mm/hugetlbpage.rst.
1023 delayacct [KNL] Enable per-task delay accounting
1036 [HW] Report power status in /proc/i8k
1070 disable= [IPV6]
1074 Disable RADIX MMU mode on POWER9
1077 Disable TLBIE instruction. Currently does not work
1085 disable BSP to wake up multiple CPUs without
1090 Disable Dynamic DMA Window support. Use this
1108 Disable PIN 1 of APIC timer
1111 dis_ucode_ldr [X86] Disable the microcode loader.
1118 entries for DMA-API debugging code. One entry is
1119 required per DMA-API allocation. Use this if the
1120 DMA-API debugging code disables itself because the
1124 With this option the DMA-API debugging driver
1144 are enabled. In order to disable RFDS mitigation all
1148 Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
1162 Generic built-in EDID data sets are used, if one of
1167 available in Documentation/admin-guide/edid.rst. An EDID
1179 Control how the dt_cpu_ftrs device-tree binding is
1189 what data is available or for reverse-engineering.
1194 Documentation/admin-guide/dynamic-debug-howto.rst
1205 determined by stdout-path property in device tree's
1210 Start an early, polled-mode console on a Cadence
1211 (xuartps) serial port at the specified address. Only
1213 specified, the serial port must already be setup and
1221 Start an early, polled-mode console on the 8250/16550
1222 UART at the specified I/O port or MMIO address.
1223 MMIO inter-register address stride is either 8-bit
1224 (mmio) or 32-bit (mmio32 or mmio32be).
1234 Start an early, polled-mode console on a pl011 serial
1235 port at the specified address. The pl011 serial port
1238 the driver will use only 32-bit accessors to read/write
1242 Start an early console on a litex serial port at the
1243 specified address. The serial port must already be
1247 Start an early, polled-mode console on a meson serial
1248 port at the specified address. The serial port must
1253 Start an early, polled-mode console on an msm serial
1254 port at the specified address. The serial port
1259 Start an early, polled-mode console on an msm serial
1260 dm port at the specified address. The serial port
1265 Start an early, polled-mode console on a serial port
1267 specified address. The serial port must already be
1271 Start an early, polled-mode console on a serial port
1273 specified address. The serial port must already be
1277 Use RISC-V SBI (Supervisor Binary Interface) for early
1290 a correct base address of the selected UART port. The
1291 serial port must already be setup and configured.
1295 Start an early, polled-mode console on a lantiq serial
1296 (lqasc) port at the specified address. The serial port
1305 port must already be setup and configured.
1309 Start an early, polled-mode, output-only console on the
1314 Start an early, polled-mode console on the
1315 Armada 3700 serial port at the specified
1316 address. The serial port must already be setup
1320 Start an early, polled-mode console on a Qualcomm
1321 Generic Interface (GENI) based serial port at the
1322 specified address. The serial port must already be
1328 coherent non-x86 systems that use system memory for
1335 address must be provided, and the serial port must
1353 Append ",keep" to not disable it when the real console
1356 Only one of vga, serial, or usb debug port can
1362 replacing ttySn with an I/O port address, like this:
1364 You can find the port for a given device in
1366 2: uart:ST16650V2 port:00001008 irq:18 ...
1382 edac_report= [HW,EDAC] Control how to report EDAC event
1386 off: disable H/W event reporting through EDAC.
1398 disable_early_pci_dma: disable the busmaster bit on all
1400 nochunk: disable reading files in "chunks" in the EFI
1403 noruntime : disable EFI runtime services support
1407 claim. Specify efi=nosoftreserve to disable this
1428 attribute is added to range 0x100000000-0x180000000 and
1429 0x10a0000000-0x1120000000.
1433 range 0x240000000-0x43fffffff.
1445 Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
1460 via a serial port see kgdboc_earlycon instead.
1462 elanfreq= [X86-32]
1470 See Documentation/admin-guide/kdump/kdump.rst for details.
1486 0 -- permissive (log only, no denials).
1487 1 -- enforcing (deny and log).
1493 Disable Error Record Serialization Table (ERST)
1519 See also Documentation/fault-injection/.
1523 See Documentation/admin-guide/sysctl/net.rst for
1527 See Documentation/admin-guide/blockdev/floppy.rst.
1530 [IA-64] Avoid check_sal_cache_flush which may hang on
1535 forcepae [X86-32]
1537 Many Pentium M systems disable PAE but may have a
1571 ftrace_filter=[function-list]
1573 tracer at boot up. function-list is a comma-separated
1578 ftrace_notrace=[function-list]
1580 function-list. This list can be changed at run time
1584 ftrace_graph_filter=[function-list]
1587 function-list is a comma-separated list of functions
1591 ftrace_graph_notrace=[function-list]
1593 function-list. This list is a comma-separated list of
1613 off -- Don't create device links from firmware info.
1614 permissive -- Create device links from firmware info
1617 on -- Create device links from firmware info and use it
1619 rpm -- Like "on", but also use to order runtime PM.
1632 strict -- Default. Continue waiting on consumers to
1634 timeout -- Give up waiting on consumers and call
1642 support via parallel port (up to 5 devices per port)
1643 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1644 See also Documentation/input/devices/joystick-parport.rst
1648 gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
1653 [X86,INTEL] Control the Gather Data Sampling (GDS)
1665 force: Disable AVX to mitigate systems without
1670 off: Disable GDS mitigation.
1672 gcov_persist= [GCOV] When non-zero (default), profiling data for
1682 gpio-mockup.gpio_mockup_ranges
1685 gpio-mockup.gpio_mockup_named_lines
1717 against bounds-checking flaws in the kernel's
1720 off Disable hardened usercopy checks.
1723 [KNL] Should the hard-lockup detector generate
1729 for 64-bit NUMA, off otherwise.
1732 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1738 Disable Hardware Error Source Table (HEST) support;
1739 corresponding firmware-first mode error processing
1746 no Disable hibernation and resume.
1749 during restoration read-only).
1756 highres= [KNL] Enable/disable high resolution timer mode.
1775 hpet= [X86-32,HPET] option to control HPET usage
1776 Format: { enable (default) | disable | force |
1778 disable: disable HPET and use PIT instead
1792 number of pages to allocate per-node can be specified.
1793 See also Documentation/admin-guide/mm/hugetlbpage.rst.
1804 Documentation/admin-guide/mm/hugetlbpage.rst.
1815 boot-time allocation of gigantic hugepages is skipped.
1820 Control if HugeTLB Vmemmap Optimization (HVO) is enabled.
1826 off: disable HVO
1843 by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
1849 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1865 [HW] Enable printing of interrupt data from the KBD port
1866 (disabled by default, and as a pre-condition
1868 i8042.direct [HW] Put keyboard port into non-translated mode
1870 keyboard and cannot control its state
1872 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
1873 i8042.nokbd [HW] Don't check/create keyboard port
1874 i8042.noloop [HW] Disable the AUX Loopback command while probing
1875 for the AUX port
1882 suspend-to-ram transitions, only during s2r
1890 i8042.kbdreset [HW] Reset device connected to KBD port
1906 -1 -- never invert brightness
1907 0 -- machine default
1908 1 -- force brightness inversion
1918 will use a lot of power and make the system run hot.
1922 idle=nomwait: Disable mwait for CPU C-states
1950 legacy only accept legacy-NaN binaries, if supported
1952 2008 only accept 2008-NaN binaries, if supported
1961 'relaxed' straps the emulator for both legacy-NaN and
1962 2008-NaN, whereas 'strict' enables legacy-NaN only on
1971 Ignore loglevel setting - this will print /all/
2038 Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
2039 "ima-sigv2" }
2040 Default: "ima-ng"
2063 indirect_target_selection= [X86,Intel] Mitigation control for Indirect
2068 off: Disable mitigation.
2073 stuff: Deploy RSB-fill mitigation when retpoline is
2078 Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
2089 initcall_blacklist= [KNL] Do not execute a comma-separated list of
2090 initcall functions. Useful for debugging built-in
2131 int_pln_enable [X86] Enable power limit notification interrupt
2135 0 -- basic integrity auditing messages. (Default)
2136 1 -- additional integrity auditing messages.
2142 Disable intel iommu driver.
2164 could harm performance of some high-throughput
2173 1 to 9 specify maximum depth of C-state.
2176 disable
2182 algorithms for p-state selection. There are two
2183 P-state selection algorithms provided by
2186 on whether or not the hardware managed P-states
2193 used along with the hardware-managed P-states (HWP)
2197 in favor of acpi-cpufreq. Forcing the intel_pstate driver
2198 instead of acpi-cpufreq may disable platform features, such
2199 as thermal controls and power capping, that rely on ACPI
2200 P-States information being indicated to OSPM and therefore
2203 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
2205 Do not enable hardware P state control (HWP)
2209 hardware P state control (HWP) if available.
2212 Description Table, specifies preferred power management
2216 Allow per-logical-CPU P-State performance control limits using
2219 intremap= [X86-64, Intel-IOMMU]
2221 off disable Interrupt Remapping
2222 nosid disable Source ID checking
2224 BIOS x2APIC opt-out request will be ignored
2225 nopost disable Interrupt Posting
2227 iomem= Disable strict checking of access to MMIO memory
2244 Disable IOMMU bypass, using IOMMU for PCI devices.
2246 iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices.
2248 0 - Try to allocate a 32-bit DMA address first, before
2250 1 - Allocate directly from the full usable range,
2252 greater than 32-bit addressing.
2256 0 - Lazy mode.
2262 1 - Strict mode.
2265 unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
2267 legacy driver-specific options takes precedence.
2272 0 - Use IOMMU translation for DMA.
2273 1 - Bypass the IOMMU for DMA.
2274 unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
2276 io7= [HW] IO7 for Marvel-based Alpha systems
2282 Standard port 0x80 based delay
2284 Alternate port 0xed based delay (needed on some systems)
2291 See Documentation/admin-guide/nfs/nfsroot.rst.
2315 Enables support for pseudo-NMIs in the kernel. This
2334 [Deprecated - use cpusets instead]
2335 Format: [flag-list,]<cpu-list>
2341 Disable the tick when a single task runs.
2358 advised to use cpusets instead to disable scheduler load
2366 "number of CPUs in system - 1".
2392 The format of <cpu-list> is described above.
2396 ivrs_ioapic [HW,X86-64]
2397 Provide an override to the IOAPIC-ID<->DEVICE-ID
2401 For example, to map IOAPIC-ID decimal 10 to
2407 * To map IOAPIC-ID decimal 10 to PCI device 00:14.0
2410 * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
2414 ivrs_hpet [HW,X86-64]
2415 Provide an override to the HPET-ID<->DEVICE-ID
2419 For example, to map HPET-ID decimal 10 to
2425 * To map HPET-ID decimal 0 to PCI device 00:14.0
2428 * To map HPET-ID decimal 10 to PCI segment 0x1 and
2432 ivrs_acpihid [HW,X86-64]
2433 Provide an override to the ACPI-HID:UID<->DEVICE-ID
2437 For example, to map UART-HID:UID AMD0020:0 to
2443 * To map UART-HID:UID AMD0020:0 to PCI segment is 0,
2446 * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
2467 kernelcore= [KNL,X86,IA-64,PPC]
2470 the kernel for non-movable allocations. The requested
2480 subsystem. Note that allocations like PTEs-from-HighMem
2488 for non-movable allocations and remaining memory is used
2492 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
2495 port as it is probed via PCI. The poll interval is
2497 each poll cycle to the debug port in case you need
2499 gdb or control-c on the dbgp connection. When
2500 not using this parameter you use sysrq-g to break into
2505 or a supported polling keyboard driver (non-usb).
2532 Configure the RouterBoard 532 series on-chip
2535 kmemleak= [KNL] Boot-time kmemleak enable/disable
2541 kprobe_event=[probe-list]
2543 The probe-list is a semicolon delimited list of probe
2554 kpti= [ARM64] Control page table isolation of user
2573 execution by eliminating the write-protection faults
2618 back to huge pages. If the value is a non-zero N, KVM will
2623 kvm-amd.nested= [KVM,AMD] Control nested virtualization feature in
2626 kvm-amd.npt= [KVM,AMD] Control KVM's use of Nested Page Tables,
2627 a.k.a. Two-Dimensional Page Tables. Default is 1
2628 (enabled). Disable by KVM if hardware lacks support
2631 kvm-arm.mode=
2634 none: Forcefully disable KVM.
2636 nvhe: Standard nVHE-based mode, without support for
2639 protected: nVHE-based mode with support for guests whose
2642 nested: VHE-based mode with support for nested
2647 mode to "protected" will disable kexec and hibernation
2651 kvm-arm.vgic_v3_group0_trap=
2652 [KVM,ARM] Trap guest accesses to GICv3 group-0
2655 kvm-arm.vgic_v3_group1_trap=
2656 [KVM,ARM] Trap guest accesses to GICv3 group-1
2659 kvm-arm.vgic_v3_common_trap=
2663 kvm-arm.vgic_v4_enable=
2675 kvm-intel.ept= [KVM,Intel] Control KVM's use of Extended Page Tables,
2676 a.k.a. Two-Dimensional Page Tables. Default is 1
2677 (enabled). Disable by KVM if hardware lacks support
2680 kvm-intel.emulate_invalid_guest_state=
2681 [KVM,Intel] Control whether to emulate invalid guest
2682 state. Ignored if kvm-intel.enable_unrestricted_guest=1,
2688 kvm-intel.flexpriority=
2689 [KVM,Intel] Control KVM's use of FlexPriority feature
2690 (TPR shadow). Default is 1 (enabled). Disable by KVM if
2693 kvm-intel.nested=
2694 [KVM,Intel] Control nested virtualization feature in
2697 kvm-intel.unrestricted_guest=
2698 [KVM,Intel] Control KVM's use of unrestricted guest
2700 is 1 (enabled). Disable by KVM if EPT is disabled or
2703 kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
2704 CVE-2018-3620.
2715 kvm-intel.vpid= [KVM,Intel] Control KVM's use of Virtual Processor
2717 (enabled). Disable by KVM if hardware lacks support
2721 Control mitigation for L1D based snooping vulnerability.
2735 on - enable the interface for the mitigation
2737 l1tf= [X86] Control mitigation of the L1TF vulnerability on
2749 SMT control and L1D flush control via the
2758 flush runtime control. Implies the
2760 (i.e. sysfs control of SMT is disabled.)
2767 SMT control and L1D flush control via the
2779 SMT control and L1D flush control via the
2800 For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
2806 lapic [X86-32,APIC] Enable the local APIC even if BIOS
2810 value for LAPIC timer one-shot implementation. Default
2815 in C2 power state.
2817 libata.dma= [LIBATA] DMA control
2818 libata.dma=0 Disable all PATA and SATA DMA
2833 libata.force= [LIBATA] Force configurations. The format is a comma-
2834 separated list of "[ID:]VAL" where ID is PORT[.DEVICE].
2835 PORT and DEVICE are decimal numbers matching port, link
2838 omitted, the last PORT and DEVICE values are used. If
2843 the port and all links and devices behind it. DEVICE
2845 first fan-out link behind PMP device. It does not
2855 Any ID with matching PORT is used.
2859 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
2866 * rstonce: only attempt one reset during hot-unplug
2869 * [no]dbdelay: Enable or disable the extra 200ms delay
2875 * [no]ncqtrim: Enable or disable queued DSM TRIM.
2877 * [no]ncqati: Enable or disable NCQ trim on ATI chipset.
2879 * [no]trim: Enable or disable (unqueued) TRIM.
2892 * [no]dmalog: Enable or disable the use of the
2895 * [no]iddevlog: Enable or disable access to the
2898 * [no]logdir: Enable or disable access to the general
2909 * [no]lpm: Enable or disable link power management.
2914 * [no]fua: Disable or enable FUA (Force Unit Access)
2919 * disable: Disable this device.
2929 lockd.nlm_tcpport=N [NFS] Assign TCP port.
2935 lockd.nlm_udpport=M [NFS] Assign UDP port.
2948 Set the number of locking read-acquisition kthreads.
2953 Set the number of locking write-acquisition kthreads.
2956 Set time (s) after boot for CPU-hotplug testing.
2959 Set time (s) between CPU-hotplug operations, or
2960 zero to disable CPU-hotplug testing.
2963 Set task-shuffle interval (jiffies). Shuffling
2964 tasks allows some CPUs to go into dyntick-idle
2969 is useful for hands-off automated testing.
2985 Run the write-side locktorture kthreads at
2986 sched_set_fifo() real-time priority.
3006 7 (KERN_DEBUG) debug-level messages
3009 in bytes. n must be a power of two and greater
3016 logo.nologo [FB] Disables display of the built-in Linux logo.
3022 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
3023 lp=reset first parallel port). 'lp=0' disables the
3029 lp0. A port specification may be 'none' to skip
3032 port specification list means that device IDs
3033 from each port should be examined, to see if
3034 an IEEE 1284-compliant printer is attached; if
3040 time-consuming boot-time autodetection (up to 250 ms per
3061 machvec= [IA-64] Force the use of a particular machine-vector
3067 Example: machtype=lemote-yeeloong-2f-7inch
3069 max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater
3082 (loop.max_loop) unconditionally pre-created at init time. The default
3085 devices can be requested on-demand with the
3086 /dev/loop-control interface.
3088 mce [X86-32] Machine Check Exception
3090 mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
3093 See Documentation/admin-guide/md.rst.
3100 Control mitigation for the Micro-architectural Data
3115 full - Enable MDS mitigation on vulnerable CPUs
3116 full,nosmt - Enable MDS mitigation and disable
3118 off - Unconditionally disable MDS mitigation
3120 On TAA-affected machines, mds=off can be prevented by
3122 mitigated with the same mechanism so in order to disable
3129 For details see: Documentation/admin-guide/hw-vuln/mds.rst
3143 [ARC,MICROBLAZE] - the limit applies only to low memory,
3146 [ARM64] - only limits memory covered by the linear
3159 [ARM,MIPS] - override the memory layout reported by
3166 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
3173 per-device physically contiguous DMA buffers.
3181 See Documentation/admin-guide/mm/memory-hotplug.rst.
3206 Example: Exclude memory from 0x18690000-0x1869ffff
3220 memmap=<size>%<offset>-<oldtype>+<newtype>
3222 from <oldtype> to <newtype>. If "-<oldtype>" is left
3237 repeatable BIOS-originated corruption always
3273 default : 0 <disable>
3281 mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control
3287 Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
3291 s2idle - Suspend-To-Idle
3292 shallow - Power-On Suspend or equivalent (if supported)
3293 deep - Suspend-To-RAM or equivalent (if supported)
3294 See Documentation/admin-guide/pm/sleep-states.rst.
3296 mfgpt_irq= [IA-32] Specify the IRQ to use for the
3297 Multi-Function General Purpose Timers on AMD Geode
3300 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
3303 problem by letting the user disable the workaround.
3309 Enable or disable the microcode minimal revision
3312 min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this
3319 0 - The attached screen is the 3.5" TFT
3320 1 - The attached screen is the 7" TFT
3321 2 - The VGA Shield is attached (1024x768)
3325 b - Enable backlight. The TFT backlight pin will be
3329 c - Enable the s3c camera interface.
3330 t - Reserved for enabling touchscreen support. The
3332 kernel as of 2.6.30, a preliminary port can be found
3334 https://repo.or.cz/w/linux-2.6/mini2440.git
3337 [X86,PPC,S390,ARM64] Control optional mitigations for
3339 arch-independent options, each of which is an
3340 aggregation of existing arch-specific options.
3346 Disable all optional CPU mitigations. This
3369 ssbd=force-off [ARM64]
3382 have other ways of avoiding SMT-based attacks.
3397 parameter allows control of the logging verbosity for
3404 [X86,INTEL] Control mitigation for the Processor
3417 full - Enable mitigation on vulnerable CPUs
3419 full,nosmt - Enable mitigation and disable SMT on
3422 off - Unconditionally disable mitigation
3428 disable this mitigation, you need to specify
3435 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
3440 probe on this module. Otherwise, enable/disable
3446 by default. To enable/disable async probing for a
3447 specific module, use the module specific control that
3465 module_blacklist= [KNL] Do not load a comma-separated list of
3479 movablecore= [KNL,X86,IA-64,PPC]
3490 movable_node [KNL] Boot-time switch to make hotplugable memory
3497 Format: <name>,<region-number>,<size>,<offset>
3500 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
3506 ARM/S3C2412 JIVE boot control
3508 See arch/arm/mach-s3c/mach-jive.c
3544 something different and driver-specific.
3555 0 to disable accounting
3573 [NFS] set the TCP port on which the NFSv4 callback
3577 [NFS] enable 64-bit inode numbers.
3578 If zero, the NFS client will fake up a 32-bit inode
3580 of returning the full 64-bit number.
3581 The default is to return 64-bit inode numbers.
3616 [NFS4] Specify an additional fixed unique ident-
3647 driver. A non-zero value sets the minimum interval
3652 server-to-server copies for which this server is
3664 server-to-server copy, knfsd temporarily mounts
3671 See Documentation/admin-guide/nfs/nfsroot.rst.
3673 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
3674 See Documentation/admin-guide/nfs/nfsroot.rst.
3677 See Documentation/admin-guide/nfs/nfsroot.rst.
3681 NMI stack-backtrace request.
3690 0 - turn hardlockup detector in nmi_watchdog off
3691 1 - turn hardlockup detector in nmi_watchdog on
3695 To disable both hard and soft lockup detectors,
3703 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
3707 no4lvl [RISCV] Disable 4-level and 5-level paging modes. Forces
3708 kernel to use 3-level paging instead.
3710 no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces
3711 kernel to use 4-level paging instead.
3714 caches in the slab allocator. Saves per-node memory,
3725 noautogroup Disable scheduler automatic task group creation.
3731 Disable suspending of consoles during suspend and
3739 console_suspend, a printk module parameter to control
3745 [KNL] Disable object debugging
3747 nodsp [SH] Disable hardware DSP at boot time.
3749 noefi Disable EFI runtime services support.
3751 no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel.
3753 noexec [IA-64]
3755 noexec32 [X86-64]
3756 This affects only 32-bit executables.
3757 noexec32=on: enable non-executable mappings (default)
3759 noexec32=off: disable non-executable mappings
3766 nofpu [MIPS,SH] Disable hardware FPU at boot time.
3770 nofxsr [BUGS=X86-32] Disables x86 floating point extended
3772 legacy floating-point registers on task switch.
3774 nohalt [IA-64] Tells the kernel not to use the power saving
3776 power-consumption. On the positive side, it reduces
3777 interrupt wake-up latency, which may improve performance
3779 real-time systems.
3789 compared. However, if this command-line option is
3795 nohibernate [HIBERNATION] Disable hibernation and resume.
3802 correctly or when doing power measurements to evaluate
3806 nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
3808 nohugevmalloc [KNL,X86,PPC,ARM64] Disable kernel huge vmalloc mappings.
3810 nohz= [KNL] Boottime enable/disable dynamic ticks
3830 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
3832 [Deprecated - use intremap=off]
3834 nointroute [IA-64]
3836 noinvpcid [X86] Disable the INVPCID cpu feature.
3838 noiotrap [SH] Disables trapped I/O port accesses.
3840 noirqdebug [X86-32] Disables the code which attempts to detect and
3841 disable unhandled interrupt sources.
3845 nojitter [IA-64] Disables jitter checking for ITC timers.
3852 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
3855 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
3857 nolapic [X86-32,APIC] Do not enable or use the local APIC.
3859 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
3861 nomca [IA-64] Disable machine check abort handling
3863 nomce [X86-32] Disable Machine Check Exception
3865 nomfgpt [X86-32] Disable Multi-Function General Purpose
3868 nomodeset Disable kernel modesetting. Most systems' firmware
3871 not load if they could possibly displace the pre-
3874 perform display-mode changes or accelerated rendering.
3878 nomodule Disable module load
3880 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
3884 nopat [X86] Disable PAT (page attribute table extension of
3887 nopcid [X86-64] Disable the PCID cpu feature.
3889 nopku [X86] Disable Memory Protection Keys CPU feature found
3892 nopti [X86-64]
3908 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
3914 nosbagart [IA-64]
3916 no-scroll [VGA] Disables scrollback.
3917 This is required for the Braillex ib80-piezo Braille
3920 nosgx [X86-64,SGX] Disables Intel SGX kernel support.
3923 Disable SMAP (Supervisor Mode Access Prevention)
3927 Disable SMEP (Supervisor Mode Execution Prevention)
3931 and disable the IO APIC. legacy for "maxcpus=0".
3933 nosmt [KNL,MIPS,PPC,S390] Disable symmetric multithreading (SMT).
3936 [KNL,X86,PPC] Disable symmetric multithreading (SMT).
3937 nosmt=force: Force disable SMT, cannot be undone
3938 via the sysfs control file.
3940 nosoftlockup [KNL] Disable the soft-lockup detector.
3943 [HW] Disable all mitigations for the Speculative Store Bypass vulnerability
3945 nospectre_bhb [ARM64] Disable all mitigations for Spectre-BHB (branch
3949 nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
3953 nospectre_v2 [X86,PPC_E500,ARM64] Disable all mitigations for
3958 no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES] Disable paravirtualized
3968 [PPC] Don't flush the L1-D cache after accessing user data.
3971 Disable device dump. Device dump allows drivers to
3981 no-vmw-sched-clock
3982 [X86,PV_OPS] Disable paravirtualized VMware scheduler
3985 nowatchdog [KNL] Disable both lockup detectors, i.e.
3986 soft-lockup and NMI watchdog (hard-lockup).
3990 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
3998 enabling legacy floating-point and sse state.
4024 nptcg= [IA-64] Override max number of concurrent global TLB
4033 n. So during boot up some boot time memory for per-cpu
4034 variables need be pre-allocated for later physical cpu
4039 numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
4042 numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
4044 Allowed values are enable and disable
4049 See Documentation/admin-guide/sysctl/vm.rst for details.
4052 See Documentation/core-api/debugging-via-ohci1394.rst for more
4067 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
4071 boundary - index of last SLC block on Flex-OneNAND.
4073 lock - Configure if Flex-OneNAND boundary should be locked.
4084 [KNL] Boolean flag to control whether the page allocator
4087 running on a platform with a direct-mapped memory-side
4089 override/disable that behavior. The state of the flag
4093 page_owner= [KNL] Boot-time page_owner enabling option.
4099 page_poison= [KNL] Boot-time parameter changing the state of
4126 See Documentation/admin-guide/tainted-kernels.rst for
4147 parkbd.port= [HW] Parallel port number the keyboard adapter is
4150 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
4162 settings on that particular port), or 'nofifo'
4169 Configure VIA parallel port to operate in
4172 up parallel port mode and sets it to spp.
4178 Set to non-zero to probe primary and secondary ISA
4179 port ranges on PCI systems where no PCI PATA device
4184 Set to non-zero if a chip is present that snoops speed
4232 Set to non-zero to probe tertiary and further ISA
4233 port ranges on PCI systems. Disabled by default.
4243 the first port in the list above (0x1f0), and so on.
4248 Set to non-zero to probe QDI controllers. By default
4253 Set to non-zero to probe Winbond controllers. Use
4254 the standard I/O port (0x130) if 1, otherwise the
4255 value given is the I/O port to use (typically 0x1b0).
4300 bios [X86-32] force use of PCI BIOS, don't access
4302 has a non-standard PCI host bridge.
4303 nobios [X86-32] disallow use of PCI BIOS, only direct
4308 Mechanism 1 (config address in IO port 0xCF8,
4309 data in IO port 0xCFC, both 32-bit).
4311 Mechanism 2 (IO port 0xCF8 is an 8-bit port for
4312 the function, IO port 0xCFA, also 8-bit, sets
4314 through ports 0xC000-0xCFFF).
4319 disable the use of PCIE advanced error reporting.
4320 nodomains [PCI] Disable support for multiple PCI
4321 root domains (aka PCI segments, in ACPI-speak).
4322 nommconf [X86] Disable use of MMCONFIG for PCI
4329 disable the use of MSI interrupts system-wide.
4330 noioapicquirk [APIC] Disable all boot interrupt quirks.
4334 primary IO-APIC for bridges that cannot disable
4337 noioapicreroute [APIC] Disable workaround that uses the
4341 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
4365 F0000h-100000h range.
4370 assign-busses [X86] Always assign all PCI bus
4391 <linux-pci@vger.kernel.org>.
4395 a bug to <linux-pci@vger.kernel.org>.
4407 bfsort Sort PCI devices into breadth-first order.
4410 nobfsort Don't sort PCI devices into breadth-first order.
4411 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
4412 tuning and use the BIOS-configured MPS defaults.
4422 configuration allows peer-to-peer DMA between
4425 that hot-added devices will work.
4440 A PCI-PCI bridge can be specified if resource
4446 for 4096-byte alignment.
4447 ecrc= Enable/disable PCIe ECRC (transaction layer
4448 end-to-end CRC checking). Only effective if
4449 OS has native AER control (either granted by
4471 realloc= Enable/disable reallocating PCI bridge resources
4479 noats [PCIE, Intel-IOMMU, AMD-IOMMU]
4483 port.
4504 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
4506 off Disable ASPM.
4510 pcie_ports= [PCIE] PCIe port services handling:
4515 dpc-native Use native PCIe service for DPC only. May
4517 compat Disable native PCIe services (PME, AER, DPC, PCIe
4520 pcie_port_pm= [PCIE] PCIe port power management handling:
4521 off Disable power management of all PCIe ports
4522 force Forcibly enable power management of all PCIe ports
4532 Keep all power-domains already enabled by bootloader on,
4537 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
4549 pirq= [SMP,APIC] Manual mp-table setup
4550 See Documentation/arch/x86/i386/IO-APIC.rst.
4552 plip= [PPT,NET] Parallel port network link
4554 See also Documentation/admin-guide/parport.rst.
4556 pmtmr= [X86] Manual setup of pmtmr I/O Port.
4573 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
4582 { on | off | curr | res | no-curr | no-res }
4591 Ranges are in pairs (I/O port base and size).
4602 Format: <port>,<port>....
4604 powersave=off [PPC] This option disables power saving features.
4618 Disable Hardware Transactional Memory
4622 none - Limited to cond_resched() calls
4623 voluntary - Limited to cond_resched() and might_sleep() calls
4624 full - Any section that isn't explicitly preempt disabled
4627 print-fatal-signals=
4633 coredump - etc.
4636 you might want to try "ulimit -i unlimited".
4643 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4647 Disable console loglevel raise on oops, panic
4648 or lockdep-detected issues (only if lock debug is on).
4656 Control writing to /dev/kmsg.
4657 on - unlimited logging to /dev/kmsg from userspace
4658 off - logging to /dev/kmsg disabled
4659 ratelimit - ratelimit the logging
4663 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4670 - 'always': traditional behavior always allows mem overrides.
4671 - 'ptrace': only allow mem overrides for active ptracers.
4672 - 'never': never allow mem overrides.
4676 Limit processor to maximum C-state
4680 Ignore the _CST method to determine C-states,
4687 Param: "schedule" - profile schedule points.
4688 Param: "kvm" - profile VM exits.
4689 Param: <number> - step/bucket size as a power of 2 for
4699 psi= [KNL] Enable or disable pressure stall information
4718 pti= [X86-64] Control Page Table Isolation of user and
4723 on - unconditionally enable
4724 off - unconditionally disable
4725 auto - kernel detects whether your CPU model is
4731 [KNL] Number of legacy pty's. Overwrites compiled-in
4734 quiet [KNL] Disable most log messages
4739 Disable RADIX GTSE feature and use hcall for TLB
4743 See Documentation/admin-guide/md.rst.
4746 See Documentation/admin-guide/blockdev/ramdisk.rst.
4751 [KNL] Disable trusting the use of the CPU's
4756 [KNL] Disable trusting the use of the a seed
4761 [KNL] Enable or disable kernel stack offset
4765 cross-syscall address exposures. This is only
4768 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
4771 ras=option[,option,...] [KNL] RAS-specific options
4774 Disable the Correctable Errors Collector,
4777 rcu_nocbs[=cpu-list]
4782 enable the no-callback CPU mode, which prevents
4787 "p" for RCU-preempt, "s" for RCU-sched, and "g"
4791 and real-time workloads. It can also improve
4795 list of CPUs is set to no-callback mode from boot.
4799 no-callback mode from boot but the mode may be
4810 This improves the real-time response for the
4827 RCU grace-period cleanup.
4831 RCU grace-period initialization.
4835 RCU grace-period pre-initialization, that is,
4836 the propagation of recent CPU-hotplug changes up
4840 Set delay from grace-period initialization to
4853 soliciting quiescent-state help from
4865 Set the SCHED_FIFO priority of the RCU per-CPU
4868 and for the RCU grace-period kthreads (rcu_bh,
4870 set, valid values are 1-99 and the default is 1
4871 (the least-favored priority). Otherwise, when
4872 RCU_BOOST is not set, valid values are 0-99 and
4873 the default is zero (non-realtime operation).
4878 On callback-offloaded (rcu_nocbs) CPUs,
4881 use of the ->nocb_bypass list. However, in the
4882 common non-flooded case, RCU queues directly to
4883 the main ->cblist in order to avoid the extra
4884 overhead of the ->nocb_bypass list and its lock.
4886 a single jiffy, RCU pre-queues the callbacks into
4887 the ->nocb_bypass queue. The definition of "too
4896 batch limiting is re-enabled.
4900 RCU's force-quiescent-state scan will aggressively
4905 disable more aggressive help enlistment.
4908 Set the page-cache refill delay (in milliseconds)
4909 in response to low-memory conditions. The range
4913 Set the shift-right count to use to compute
4914 the callback-invocation batch limit bl from
4921 Please note that this callback-invocation batch
4922 limit applies only to non-offloaded callback
4928 Disable autobalancing of the rcu_node combining
4931 cache-to-cache transfer latencies.
4937 and for NUMA systems with large remote-access
4953 the wakeup overhead on the global grace-period
4955 each group's NOCB grace-period kthread.
4958 Cause the grace-period kthread to get an extra
4960 it should at force-quiescent-state time.
4973 this specifies an rcu_read_unlock()-time delay
4977 of RCU-protected pointers after the relevant
4987 per-CPU rcuc kthreads. Defaults to a non-zero
4991 But note that CONFIG_PREEMPT_RT=y kernels disable
4997 grace-period primitives such as call_rcu().
5008 grace-period primitives.
5011 Set test-start holdoff period. The purpose of
5029 Test the double-argument variant of kfree_rcu().
5031 rcuscale.kfree_rcu_test_single, both the single-
5032 and double-argument variants are tested.
5035 Test the single-argument variant of kfree_rcu().
5037 rcuscale.kfree_rcu_test_double, both the single-
5038 and double-argument variants are tested.
5052 does not affect the data-collection interval,
5057 Set number of RCU readers. The value -1 selects
5059 "n" less than -1 selects N-n+1, where N is again
5060 the number of CPUs. For example, -2 selects N
5061 (the number of CPUs), -3 selects N+1, and so on.
5062 A value of "n" less than or equal to -N selects
5075 complete. This is useful for hands-off automated
5082 Write-side holdoff between grace periods,
5087 Additional write-side holdoff between grace
5105 for RCU grace-period forward-progress testing
5112 Specify the fraction of a CPU-stall-warning
5113 period to do tight-loop forward-progress testing.
5117 forward-progress tests.
5121 need_resched() during tight-loop forward-progress
5125 Use conditional/asynchronous update-side
5129 Use expedited update-side primitives, if available.
5132 Use normal (non-expedited) asynchronous
5133 update-side primitives, if available.
5136 Use normal (non-expedited) synchronous
5137 update-side primitives, if available. If all
5141 they are all non-zero.
5149 Leak an RCU-protected pointer out of the reader.
5164 Set number of RCU callback-offload togglers.
5169 callback-offload toggling attempts.
5172 Set number of RCU readers. The value -1 selects
5173 N-1, where N is the number of CPUs. A value
5174 "n" less than -1 selects N-n-2, where N is again
5175 the number of CPUs. For example, -2 selects N
5176 (the number of CPUs), -3 selects N+1, and so on.
5179 Enable debug-object double-call_rcu() testing.
5182 Set time (s) after boot for CPU-hotplug testing.
5185 Set time (jiffies) between CPU-hotplug operations,
5186 or zero to disable CPU-hotplug testing.
5189 Set the number of read-then-exit kthreads used
5191 task-exit processing.
5194 The number of times in a given read-then-exit
5195 episode that a set of read-then-exit kthreads
5200 read-then-exit testing episodes.
5203 Set task-shuffle interval (s). Shuffling tasks
5204 allows some CPUs to go into dyntick-idle mode
5209 is useful for hands-off automated testing.
5213 warnings, zero to disable.
5218 any other stall-related activity. Note that
5224 in scheduling-while-atomic splats.
5233 Disable interrupts while stalling if set.
5237 grace-period kthread to test RCU CPU stall
5238 warnings, zero to disable. If both stall_cpu
5263 Test RCU's dyntick-idle handling. See also the
5312 Use expedited grace-period primitives, for
5316 real-time latency, and degrade energy efficiency.
5320 Use only normal grace-period primitives,
5323 real-time latency, CPU utilization, and
5325 increased grace-period latency. This parameter
5332 only normal grace-period primitives. No effect
5338 post-boot attempt at an expedited RCU grace
5339 period to instead use normal non-expedited
5340 grace-period processing.
5348 set to the default value of -1.
5351 Set the minimum number of callback-queuing-time
5352 lock-contention events per jiffy required to
5353 cause the RCU Tasks flavors to switch to per-CPU
5356 the default value of -1.
5361 of -1 allows this to be automatically (and
5369 number avoids disturbing real-time workloads,
5374 cancel laziness on that CPU. Use -1 to disable
5384 only printed prior to the stall-warning message
5385 for a given grace period. Disable with a value
5403 warning messages. Disable with a value less
5412 of zero will disable batching. Batching is
5420 disable batching. Batching is always disabled
5428 disable batching. Batching is always disabled
5440 force - Override the decision by the kernel to hide the
5468 Set test-start holdoff period. The purpose of
5477 but the default has already reduced the per-pass
5482 Set number of readers. The default value of -1
5491 Set the read-side critical-section duration,
5495 Specify the read-protection implementation to test.
5514 See Documentation/admin-guide/cgroup-v1/cpusets.rst.
5522 reservetop= [X86-32]
5539 See Documentation/power/swsusp-and-swap-files.rst
5550 retbleed= [X86] Control mitigation of RETBleed (Arbitrary
5554 AMD-based UNRET and IBPB mitigations alone do not stop
5556 sibling threads. For that reason, STIBP is used on pro-
5560 off - no mitigation
5561 auto - automatically select a migitation
5562 auto,nosmt - automatically select a mitigation,
5566 ibpb - On AMD, mitigate short speculation
5571 ibpb,nosmt - Like "ibpb" above but will disable SMT
5575 unret - Force enable untrained return thunks,
5576 only effective on AMD f15h-f17h based
5578 unret,nosmt - Like unret, but will disable SMT when STIBP
5602 ring3mwait=disable
5603 [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
5613 ro [KNL] Mount root device read-only on boot
5616 on Mark read-only kernel memory as read-only (default).
5617 off Leave read-only kernel memory writable for debugging.
5618 full Mark read-only kernel memory and aliases as read-only
5622 Enable the uart passthrough on the designated usb port
5624 debug-uart get routed to the D+ and D- pins of the usb
5625 port and the regular usb controller gets disabled.
5630 block/early-lookup.c for details.
5655 rw [KNL] Mount root device read-write on boot
5683 schedstats= [KNL,X86] Enable or disable scheduled statistics.
5684 Allowed values are enable and disable. This feature
5707 to 10 seconds for built-in smp_call_function()
5714 that requesting even small non-zero numbers of
5721 The default of -1 specifies a number of kthreads
5726 test before initiating CPU-hotplug operations.
5730 CPU-hotplug operations. Specifying zero (which
5731 is the default) disables CPU-hotplug operations.
5737 Non-zero values are useful for automated tests.
5750 preempt_disable() to disable CPU hotplug
5760 "wait" parameter. A value of -1 selects the
5761 default if all other weights are -1. However,
5763 value of -1 will instead select a weight of zero.
5768 non-zero "wait" parameter. See weight_single.
5781 non-zero "wait" parameter. See weight_single
5793 non-zero "wait" parameter. See weight_single
5800 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
5801 1 -- enable.
5802 Note: increases power consumption, thus should only be
5809 selinux= [SELINUX] Disable or enable SELinux at boot time.
5812 0 -- disable.
5813 1 -- enable.
5816 serialnumber [BUGS=X86-32]
5818 sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
5826 to set it to "all" by meaning -- no limit here.
5832 simeth= [IA-64]
5842 Disable merging of slabs with similar size. May be
5846 layout control by attackers can usually be
5850 unchanged). Debug options disable merging on their
5907 using the csdlock_debug- kernel parameter.
5912 system. By default, let CSD-lock acquisition
5914 for this value provides a 5-minute timeout.
5916 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
5917 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
5918 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
5919 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
5920 smsc-ircc2.ircc_irq= [HW] IRQ line
5921 smsc-ircc2.ircc_dma= [HW] DMA channel
5922 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
5932 Default: -1 (no limit)
5935 [KNL] Should the soft-lockup detector generate panics.
5938 A value of 1 instructs the soft-lockup detector
5939 to panic the machine when a soft-lockup occurs. It is
5942 respective build-time switch to that functionality.
5945 [KNL] Should the soft-lockup detector generate
5949 sonypi.*= [HW] Sony Programmable I/O Control Device driver
5950 See Documentation/admin-guide/laptops/sonypi.rst
5952 spectre_bhi= [X86] Control mitigation of Branch History Injection
5954 deployment of the HW BHI control and the SW BHB
5957 on - (default) Enable the HW or SW mitigation
5959 off - Disable the mitigation.
5961 spectre_v2= [X86] Control mitigation of Spectre variant 2
5966 on - unconditionally enable, implies
5968 off - unconditionally disable, implies
5970 auto - kernel detects whether your CPU model is
5982 Selecting 'off' will disable both the kernel and
5987 retpoline - replace indirect branches
5988 retpoline,generic - Retpolines
5989 retpoline,lfence - LFENCE; indirect branch
5990 retpoline,amd - alias for retpoline,lfence
5991 eibrs - Enhanced/Auto IBRS
5992 eibrs,retpoline - Enhanced/Auto IBRS + Retpolines
5993 eibrs,lfence - Enhanced/Auto IBRS + LFENCE
5994 ibrs - use IBRS to protect kernel
6000 [X86] Control mitigation of Spectre variant 2
6004 on - Unconditionally enable mitigations. Is
6007 off - Unconditionally disable mitigations. Is
6010 prctl - Indirect branch speculation is enabled,
6012 per thread. The mitigation control state
6016 - Like "prctl" above, but only STIBP is
6022 - Same as "prctl" above, but all seccomp
6027 - Like "seccomp" above, but only STIBP is
6032 auto - Kernel selects the mitigation depending on
6041 [X86] Control RAS overflow mitigation on AMD Zen CPUs
6043 off - Disable mitigation
6044 microcode - Enable microcode mitigation only
6045 safe-ret - Enable sw-only safe RET mitigation (default)
6046 ibpb - Enable mitigation by issuing IBPB on
6048 ibpb-vmexit - Issue IBPB only on VMEXIT
6049 (cloud-specific mitigation)
6052 [HW] Control Speculative Store Bypass (SSB) Disable mitigation
6074 on - Unconditionally disable Speculative Store Bypass
6075 off - Unconditionally enable Speculative Store Bypass
6076 auto - Kernel detects whether the CPU model contains an
6082 prctl - Control Speculative Store Bypass per thread
6084 for a process by default. The state of the control
6086 seccomp - Same as "prctl" above, but all seccomp threads
6087 will disable SSB unless they explicitly opt out.
6094 on,auto - On Power8 and Power9 insert a store-forwarding
6098 off - No action.
6117 off - not enabled
6119 warn - the kernel will emit rate-limited warnings
6127 fatal - the kernel will send SIGBUS to applications
6132 ratelimit:N -
6149 Control the Special Register Buffer Data Sampling
6152 Certain CPUs are vulnerable to an MDS-like
6165 off: Disable mitigation and remove
6172 This kernel-boot parameter defaults to 128,
6173 but takes effect only when the low-order four
6190 instead of the compile-time CONFIG_NR_CPUS.
6194 grace-period sequence counter wrap for the
6195 srcu_data structure's ->srcu_gp_seq_needed field.
6206 expediting. Set to zero to disable automatic
6210 Specifies the number of no-delay instances
6217 Specifies the per-grace-period phase, number of
6218 non-sleeping polls of readers. Beyond this limit,
6224 Specifies number of microseconds of non-sleeping
6225 delay between each non-sleeping poll of readers.
6228 Specifies the number of update-side contention
6233 set for contention-based conversions to occur.
6236 Speculative Store Bypass Disable control
6243 force-on: Unconditionally enable mitigation for
6245 force-off: Unconditionally disable mitigation for
6261 disable the stack depot thereby saving the static memory
6268 stacktrace_filter=[function-list]
6270 will trace at boot up. function-list is a comma-separated
6278 Set the STI (builtin display/keyboard on the HP-PARISC
6280 as the initial boot-console.
6292 Enable or disable strict sigaltstack size checks
6312 originate from a privileged port (i.e. a port in the
6318 maximum port values.
6328 Control how the NFS server code allocates CPUs to
6340 to global on non-NUMA machines)
6355 /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
6363 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
6365 <int> -- Number of I/O TLB slabs
6366 <int> -- Second integer after comma. Number of swiotlb
6368 to a power of 2.
6369 force -- force using of bounce buffers even if they
6371 noforce -- Never use bounce buffers (for debugging)
6386 Ignore sysrq setting - this boot parameter will
6394 cache size. See Documentation/networking/ip-sysctl.rst
6401 Specify "mem" (for Suspend-to-RAM) or "standby" (for
6406 wakeup-capable RTC alarm.
6412 -1: disable all active trip points in all thermal zones
6416 -1: disable all critical trip points in all thermal zones
6420 1: disable ACPI thermal control
6423 -1: disable all passive trip points
6429 <deci-seconds>: poll all this frequency
6451 Prevent the CPU-hotplug component of torturing
6455 Dump the ftrace buffer at torture-test shutdown,
6459 with rotating-rust storage.
6464 disables verbose-printk() sleeping.
6467 Duration of each verbose-printk() sleep in jiffies.
6485 https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
6523 local - Use the per CPU time stamp counter
6527 global - Event time stamps are synchronize across
6530 counter - Simple counting of events (1, 2, ..)
6534 uptime - Use jiffies as the time stamp.
6535 perf - Use the same clock that perf uses.
6536 mono - Use ktime_get_mono_fast_ns() for time stamps.
6537 mono_raw - Use ktime_get_raw_fast_ns() for time
6539 boot - Use ktime_get_boot_fast_ns() for time stamps.
6543 trace_event=[event-list]
6545 to facilitate early boot debugging. The event-list is a
6546 comma-separated list of trace events to enable. See
6549 trace_instance=[instance-info]
6569 trace_options=[option-list]
6570 [FTRACE] Enable or disable tracer options at boot.
6571 The option-list is a comma delimited list of options
6585 trace_trigger=[trigger-list]
6605 [FTRACE] enable this option to disable tracing when a
6620 Can be used to control the default behavior of the system
6622 See Documentation/admin-guide/mm/transhuge.rst
6630 - "tpm"
6631 - "tee"
6632 - "caam"
6642 - "kernel"
6643 - the same value as trusted.source: "tpm" or "tee"
6644 - "default"
6648 tsa= [X86] Control mitigation for Transient Scheduler
6655 off - disable the mitigation
6656 on - enable the mitigation (default)
6657 user - mitigate only user/kernel transitions
6658 vm - mitigate only guest/host transitions
6661 tsc= Disable clocksource stability checks for TSC.
6666 high-resolution timer mode on older hardware, and in
6669 Used to run time disable IRQ_TIME_ACCOUNTING on any
6675 [x86] nowatchdog: disable clocksource watchdog. Used
6696 tsx= [X86] Control Transactional Synchronization
6698 support TSX control.
6702 on - Enable TSX on the system. Although there are
6705 several previous speculation-related CVEs, and
6709 off - Disable TSX on the system. (Note that this
6717 auto - Disable TSX if X86_BUG_TAA is present,
6722 See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6725 tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
6728 Similar to Micro-architectural Data Sampling (MDS)
6743 full - Enable TAA mitigation on vulnerable CPUs
6746 full,nosmt - Enable TAA mitigation and disable SMT on
6749 vulnerable to cross-thread TAA attacks.
6750 off - Unconditionally disable TAA mitigation
6752 On MDS-affected machines, tsx_async_abort=off can be
6754 are mitigated with the same mechanism so in order to disable
6764 Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
6767 TurboGraFX parallel port interface
6769 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
6770 See also Documentation/input/devices/joystick-parport.rst
6772 udbg-immortal [PPC] When debugging early kernel crashes that
6778 Set number of hash buckets for UDP/UDP-Lite connections
6780 uhci-hcd.ignore_oc=
6782 Some badly-designed motherboards generate lots of
6791 unwind_debug [X86-64]
6799 (default -1 = authorized (same as 1),
6801 if device connected to internal port)
6805 for newly-detected USB devices (default 2). This
6833 [USB] Specifies timeout for the initial 64-byte
6837 usbcore.nousb [USB] Disable the USB subsystem
6840 [USB] A list of quirk entries to augment the built-in
6843 VendorID:ProductID:Flags. The IDs are 4-digit hex
6845 will change the built-in quirk; setting it if it is
6850 a 255-byte read);
6854 Set-Interface requests);
6873 (bInterval-1).
6885 Power Management);
6894 pause after every control message);
6896 delay after resetting its port);
6911 usb-storage.delay_use=
6915 usb-storage.quirks=
6917 override the built-in unusual_devs list. List
6920 and Product ID values (4-digit hex numbers) and
6922 to a common usb-storage quirk flag as follows:
6964 medium is write-protected).
6973 1 - undefined instruction events
6974 2 - system calls
6975 4 - invalid data aborts
6976 8 - SIGSEGV faults
6977 16 - SIGBUS faults
6991 vdso=0: disable VDSO mapping
6993 vdso32= [X86] Control the 32-bit vDSO
6994 vdso32=1: enable 32-bit VDSO
6995 vdso32=0 or vdso32=2: disable 32-bit VDSO
7005 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
7007 vector= [IA-64,SMP]
7039 vga= [BOOT,X86-32] Select a particular video mode
7041 Documentation/admin-guide/svga.rst.
7056 - Disable all of the above options
7074 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
7077 vsyscall= [X86-64]
7080 code). Most statically-linked binaries and older
7083 targets for exploits that can control RIP.
7104 see VGA-softcursor.txt. Default: 2 = underline.
7109 This is a 16-member array composed of values
7110 ranging from 0-255.
7115 This is a 16-member array composed of values
7116 ranging from 0-255.
7121 This is a 16-member array composed of values
7122 ranging from 0-255.
7127 Set system-wide default UTF-8 mode for all tty's.
7128 Default is 1, i.e. UTF-8 mode is enabled for all
7133 Format=<-1|0|1>
7134 Set system-wide default for whether a cursor
7135 is shown on new VTs. Default is -1,
7140 vt.italic= [VT] Default color for italic text; 0-15.
7143 vt.underline= [VT] Default color for underlined text; 0-15.
7147 see Documentation/watchdog/watchdog-parameters.rst
7148 or other driver-specific files in the
7162 Format: <cpu-list>
7176 Per-cpu work items which run for longer than this
7179 them from noticeably delaying other per-cpu work
7188 Per-cpu workqueues are generally preferred because
7190 locality; unfortunately, per-cpu workqueues tend to
7191 be more power hungry than unbound workqueues.
7193 Enabling this makes the per-cpu workqueues which
7194 were observed to contribute significantly to power
7196 power usage at the cost of small performance
7207 Documentation/core-api/workqueue.rst.
7220 forces round-robin CPU selection to flush out
7225 writecombine= [LOONGARCH] Control the MAT (Memory Access Type) of
7228 on - Enable writecombine, use WUC for ioremap_wc()
7229 off - Disable writecombine, use SUC for ioremap_wc()
7231 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
7235 xen_512gb_limit [KNL,X86-64,XEN]
7245 ide-disks -- unplug primary master IDE devices
7246 aux-ide-disks -- unplug non-primary-master IDE devices
7247 nics -- unplug network devices
7248 all -- unplug all emulated devices (NICs and IDE disks)
7249 unnecessary -- unplugging emulated devices is
7252 never -- do not unplug even if version check succeeds
7260 Select whether to always use non-faulting (safe) MSR
7276 [KNL,X86,XEN] Disable the vector callback for Xen
7280 Boolean option to control scrubbing pages before giving them back
7285 xen_timer_slop= [X86-64,XEN]
7308 Boolean parameter to disable using fifo event handling
7310 preferred over the 2-level event handling, as it is
7323 off Fallback to firmware control of XIVE interrupt
7327 xive.store-eoi=off [PPC]
7333 xhci-hcd.quirks [USB,KNL]